Sodium cyanate, a chemotherapeutic agent for sickle cell disease, inhibits irreversibility of the sickling of erythrocytes from patients with the disease by reacting specifically with the NH2-terminal valine of the hemoglobin molecule without significantly destroying erythrocyte metabolism for function. We are studying whether sodium cyanate elicits neuropathologic lesions in pigtail monkeys, macaca nemastrina, as has been suggested. The outcome of this study will provide information for development of clinical studies of human beings with sickle cell disease.